Inhibition of TOR represses nutrient consumption, which improves greening after extended periods of etiolation

Abstract

Upon illumination, etiolated seedlings experience a transition from heterotrophic to photoautotrophic growth. During this process, the tetrapyrrole biosynthesis pathway provides chlorophyll for photosynthesis. This pathway has to be tightly controlled to prevent the accumulation of photoreactive metabolites and to provide stoichiometric amounts of chlorophyll for its incorporation into photosynthetic protein complexes. Therefore, plants have evolved regulatory mechanisms to synchronize the biosynthesis of chlorophyll and chlorophyll-binding proteins. Two phytochrome-interacting factors (PIF1 and PIF3) and the DELLA proteins, which are controlled by the gibberellin pathway, are key regulators..